1. Field of the Invention
The present invention relates to a particle size distribution analyzer in which measurement of the particle size distribution is accomplished based on the strength of the diffracted and/or scattered light (hereafter referred to as diffracted/scattered light) by irradiating light onto the particles distributed within the dispersion medium.
2. Background of the Related Art
(1) This type of particle size distribution analyzer such as is disclosed in Japanese Laid Open Patent 2000-146814 irradiates light from the light source of a laser and the like onto a particle stored in transparent cells, and the intensity angle distribution of the diffracted/scattered light generated at the time is detected by multiple light detectors dispersed and arranged on the periphery of the cells, in order to measure the particle size distribution of the particles based on the detected results.
Heretofore, in addition to housing a light source, or light detector, or optical system equipment between the two in a single case, a cell storage space (so-called sample chamber) has been arranged in the center of the case, so as to arrange the cells.
However, as shown in the publication, making the light source side to be of sealed construction is already known, and since the cell storage space is frequently opened by the user to accomplish cell exchange and the like, completely sealed construction is not achieved, and in reality is coupled with the space in which the detector is arranged. As a result, the space on the detector side is spatially connected to the cell storage space (sample chamber), with vacillation of the light on the light detector side being caused by counter currents of air or changes in temperature, making it difficult to make measurements with good replication.
(2) In addition, as shown in the same publication with regard to various particle size distribution analyzers, from a construction standpoint, as shown in the scaled plane diagram of FIG. 13, the light source or the light detector, or the optical system equipment located between them, is housed in a single case, in addition to which a cell storage space (a so-called sample chamber) is provided in the center of the case so as to arrange the cells. In the cell, there are various types of dispersion media, such as liquid bodies of water or alcohol, with the presence of various gaseous bodies of air and the like, classified as being wet and dry, and the dispersion medium and granules are also classified as being either a flow type or batch type, depending upon whether or not they are circulated.
With the construction referred to above, since the sample chamber is surrounded on the periphery by other equipment, access to the sample chamber is only available from above, and given the limit to the space above, since the breadth of the space is inadequate, operations such as changing the cell type in switching the measurement format, or washing the cells as part of maintenance and the like, makes for extremely poor operability when there is a need to also remove not only the cells, but also the cell holder which supports the cells. As a result, depending upon the circumstance, there are also cases in which the sample chamber itself must be removed and exchanged.
Furthermore, heretofore, in addition to basically housing the measurement system devices of a light source and light detector and the like in a single case, since there is the concept of attaching a sample chamber within the case, devising construction with airtight separation between the sample chamber within the case and other space is extremely difficult. Given the premise of such construction, even adopting a new measurement format in which spraying is performed within the sample chamber and the sprayed granule diameter is measured, there is the problem of the spray reaching the detector, making it difficult to easily adopt the new format.
In other words, in conventional devices, there was the difficulty that the construction itself became a bottleneck, with poor operability, making it difficult to introduce newly developed measurement formats.
(3) On the other hand, in Japanese Laid Open Patent Publication 2000-214068, reference is made to an example of this type of particle size distribution analyzer in which light emitted from the light source of an He—Ne laser and the like is introduced to a beam expander through a mirror, and the diameter is widened and following irradiation of the light onto the particles in the cell, generated diffracted/scattered light is received through a lens by the scattered and arranged light detectors.
With such a device, when accomplishing measurement of particle size distribution with good precision up to and including large diameter particles, detection must be accomplished also of diffracted/scattered light which has an extremely small angle from the light axis. Owing to this, the detector must be arranged extremely close to the vicinity of the optical axis, greatly increasing angle resolution ability. With such construction, it is necessary that there be accurate positional alignment of the light from the light source, and the detector.
Heretofore, in accomplishing the referenced positional alignment in the production process, the mirror is adjusted on an optical bench, and optical axis alignment is performed between the light source and the beam expander. Subsequently, in order to individually accomplish positional alignment of the lens and light detector, simultaneous fixing and adjustment must be accomplished on the optical bench for each product, which is laborious.
Furthermore, in accomplishing positional alignment, since the use of the interfering light between the light emitted from the light source and other optical products not only requires manual operation and time, there is also great concern that required skillfulness will result in aberrations produced by the operator.
In addition, when accomplishing maintenance to exchange the light source and the like as well, due to duly consider minute differences between the pre-exchange light source and the post exchange light source, in addition to the exchange, there is a need to re-adjust the entire body of the optical system, with the added inconvenience of requiring a great amount of time and effort.